The present invention relates generally to repairing cracks in asphalt or concrete surfaces, and more particularly to a method of making an extruded, direct fire crack filler material which is used to permanently repair the crack.
On a national basis, one of the most expensive investments is the system asphalt and concrete roadways. Given the expense of constructing these roadways, it is extremely important to maintain proper road conditions, both to protect the investment and permit people to travel safely and quickly.
On an individual basis, almost every home and business includes a finished traffic area, e.g., an asphalt or concrete driveway or parking lot, or even a basketball/tennis court. Apart from any buildings on the property, these areas typically represent one of the more expensive improvements on any property. Thus, it is also extremely important to properly maintain these areas to protect the investment.
Roadways, driveways, parking lots and other surfaces that are finished with asphalt and concrete crack and wear out over time, and such damage is caused by different variables. The number and size of vehicles, or lack of vehicles, traversing the surface affects the surface integrity, as a portion of the surface is compressed and then expands as each vehicle traverses that portion. Also, asphalt is very susceptible to the elements, e.g., sun, wind, rain and heat, which oxidize the asphalt. Oxidized asphalt hardens and shrinks, and breaks first at its weakest point.
The cracks and wear can be divided into several different types. A reflective crack forms when a cracked or worn surface is covered over with a new layer of surface material. Existing cracks in the underlying pavement simply reflect or migrate upwardly thorough the new layer of material. A joint crack is a result of an inherent part of the paving or concrete pouring process, since a joint is formed between segments of a surface each time a load of paving material is consumed and the next load is started. Joint cracking occurs if a proper bond does not form between the two loads of material. A slippage crack is typically the result of heavy traffic, and in the event that a proper bond is not formed between upper and lower layers of paving material, adjacent levels of material may slip or shear and crack. Thermal cracks result from temperature cycles, and the corresponding surface expansion and contraction of the pavement. Fatigue or alligator cracks occurs over time, as the surface material loses its ability to expand and contract. Since hardened material will not compress and expand vertically as vehicles pass over the material, the material cracks. Block cracks result from too little traffic, and cracks form due to the lack of vehicle weight on the material, which would otherwise compress the material. Edge cracks typically extend parallel to and within about 18 inches from the edge of finished surface, and can result from a poor subsurface, drainage or the effects of freezing-thawing water as described above.
If improperly repaired or left unmaintained, each crack enables the elements to more rapidly cause further and more expensive damage to surface and subsurface materials. Even small cracks in asphalt or concrete surfaces which are improperly repaired or left unmaintained rapidly result in extensive damage. For example, water will seep through cracks and into the subsurface materials, and freeze and thaw with temperature changes. When the water freezes and thaws, the surrounding areas expands, contracts and consolidates, and rapidly deteriorates. Thus, the small cracks, which could have been treated as a small repair job, quickly result in an expensive reconstruction project.
From the early days of asphalt and concrete surfaces, it became apparent that it was not economically feasible to simply repave a surface each time that cracks or wear appeared. A new industry arose and introduced crack fillers and crack sealers for maintaining structural integrity and obtain longer life span of the roadways, parking lots and other surfaces. As used herein, crack fillers are inserted into the cracks to reduce water intrusion and help reinforce the surrounding pavement. Crack sealers are placed above or just into the cracks in order to prevent the intrusion or water, sand, gravel and dirt into the crack. Accordingly, a properly sealed crack is preferable to crack filling for making longer-lasting repairs.
The integrity of each repair is only as good as the preparation of the crack to be repaired. A crack must be properly cleaned and prepared prior to repair. Preparation includes routing or widening narrow cracks to provide an adequate reservoir to receive sealant, wire brushing, hot or cold air blowing or sand blasting. Melted sealant is then poured into the cracks, and allowed to cool.
Over time and utilizing advances in materials and technology, the industry developed what is today considered the optimum crack repair material, a hot-poured, rubberized crack sealant which not only resists the elements, but also adheres to the sidewalls of cracks, and expands and contracts with temperature cycles. Hot-poured sealers also enable control over base and sub-base conditions, as well as pavement interference and crack growth.
Typical hot-poured sealants includes blends of asphalts, cements, extender oils, rubbers, anti-oxidants and fillers. Regardless of composition, these sealants are all hot-applied, e.g., heated to liquid form and then poured into a crack to be repaired. Once poured, the melted sealant bonds with the edges of the crack, and cools to form a proper seal with the side walls of the crack. As noted above, a properly sealed crack prevents water intrusion, as well as intrusion by loose materials such as sand and rocks.
Hot pour sealers are not easy to use, as such sealers require a measure of sophistication and knowledge of the intended use to select the proper sealant for the job. For example, the climate in which a sealant will be used greatly affects the type of sealant selected. In the Northeast, roadways are subjected to extreme temperature changes from season to season, and even from day to day. Asphalt and concrete roadway surfaces are frozen and thawed numerous times, and the repeated expansion and contraction causes substantial movement of the surface and any cracks and joints. In the South, roadways are also subject to temperature cycles, but the average temperature is much higher. In either case, the sealant must form and maintain a bond with the cracks, and also remain unaffected by the elements.
A crack repair business must make a substantial capital investment in equipment. Known equipment includes expensive melters, pumps and/or hand-operated pour-pots. A melter typically includes a "double-boiler" kettle in which large blocks, e.g., several 50 lb. blocks, of material are agitated and melted, and held for pouring. The melted material is then poured into a crack or joint, either directly from the kettle or from a hand-operated pour-pot. Unfortunately, melters are expensive, costing up to $10,000 or more.
While this arrangement provides economies of scale for the large-scale purchasers of the crack sealer material, it is impractical for the average homeowner or small business owner to purchase such equipment to maintain his or her own property. Thus, the business of installing the repair material, i.e., actually fixing cracks, remains with the manufacturers of the hot-pour materials, who provide the large blocks of material to municipalities, and to the contractors and businesses which perform the repairs using the expensive equipment described above.
As a result of the substantial expense associated with the use of hot pour crack sealers, homeowners and small businesses have basically had two alternatives for repairing cracks - retain the services of a business that has the equipment necessary to use hot pour sealer to repair the cracks, or use a cold-pour sealer and/or filler material. However, it is expensive to retain the services of a crack repair business to repair cracks, on the order of several hundreds of dollars for a mildly cracked driveway. On the other hand, the cold-pour materials do not consistently form permanent bonds with the sidewalls of the cracks nearly as well as hot-pour sealers. Consequently, repairs using cold-pour products are not permanent, and must be monitored repeatedly and repaired as necessary to prevent further cracking and expensive damage.
In addition, the hot-pour and cold-pour crack repair materials are applied as a liquid. While the drawbacks associated with hot-pour materials are discussed above, the cold pour materials have similar disadvantages. Since the cold pour materials are typically liquid or semi-liquid material, special equipment is necessary to handle the liquid material. Moreover, the cold-pour, liquid materials tend to drip or splatter during application to a crack, and thus create a sloppy appearance of the repaired crack, in addition to creating messy work equipment such as pour-pots and bottles, and where work gloves are not used - hands and clothing which are very difficult to clean. Moreover, the packaging and handling equipment for liquids must be disposed of, with associated environmental drawbacks.
It would be desirable to provide a crack sealer which overcomes the drawbacks and disadvantages of known crack repair products, while using direct fire crack sealer materials without the associated high expense.